1. Field of the Invention
The present invention relates to point-to-point or point-to-multipoint wireless communications systems. More specifically, the present invention relates to a system and method for minimizing call setup latency by ensuring adequate communication bandwidth for a group communications between wireless devices that are members of a communication group, such as push-to-talk (PTT) communication group.
2. Description of the Related Art
There exists a wireless telecommunication service that provides a quick one-to-one or one-to-many communication between groups of wireless communication devices, such as mobile telephones, that is generically referred to as “Push-To-Talk” (PTT) capability. The specific PTT group of recipient devices for the communicating wireless device is commonly set up by the carrier. A PTT communication connection is typically initiated by a single button-push on the wireless device that activates a half-duplex link between the speaker and each member device of the group and once the button is released, the device can receive incoming PTT transmissions. In some arrangements, the PTT speaker will have the “floor” where no other group member can speak while the speaker is speaking. Once the speaker releases the PTT button, any other individual member of the group can engage their PTT button and they will have the floor.
Because PTT communications involve voice, it is imperative that their transmissions get the required quality of service (“QoS”). One critical component to ensure QoS is to guarantee the network bandwidth/resources required by the PTT application are available for the voice communications. This reservation of the bandwidth and resources is difficult to implement in a dynamic fashion in a PTT system because the various group members can be distributed across heterogeneous distributed systems consisting of both fixed and variable bandwidth networks. In particular, for voice-over-internet protocol (“VoIP”) applications that consist of multiple simultaneous sessions traversing multiple systems, the problem becomes especially difficult given that each session may have different bandwidth/resource requirements.
Consequently, for PTT sessions and VoIP sessions, each session established needs to be guaranteed fixed resources in all the systems that are serving the session, and each system needs to guarantee that the maximum resources available to it are not exceeded when there are several sessions being established simultaneously. Furthermore, in the PTT call setup, the session establishment times need to be kept low.
There have been several attempts to address this problem in resources allocation for communications. One attempt utilizes centralized resource allocation where a centralized allocator keeps track of all the available resources, end-to-end for all communications. In this system, all entities that will need resources send messages to the centralized allocator requesting resources and the allocator responds with the allocated resources before setting up each session. However, the use of a centralized allocator does not scale well, and as the system expands, the centralized allocator gets heavily loaded and becomes a bottleneck for setting up communications.
Another method to address the resource allocation necessary to maintain communication quality of server is to use an “end-to-end” resource allocation system where the first portion of session establishment involves traversing through each node in the network and reserving resources in each of these nodes. While this system guarantees reserved resources throughout each system, the express step of reserving resources tremendously increases the per session communications establishment/teardown times. This type of system is often referred to as a “virtual circuit” or “socket” established in a network.
Accordingly, it would be advantageous to provide a system and method that would assist in the provision of minimum resources allocation in a PTT or VoIP communication session that does not impede call setup or teardown. Such system and method should be able to establish a reliability of resource allocation over a variety of communication systems, and be easily scalable. It is thus to the provision of such a system and method for minimizing call setup latency for a group communication between wireless communication devices that the present invention is primarily directed.